1. Field of the Invention
This invention relates to a seatbelt system for protecting an occupant in an emergency of a vehicle, and particularly to a seatbelt system wherein consideration is given to improving the occupant restraining performance by directly locking the intermediate portion of webbings for restraining an occupant in an emergency of the vehicle.
2. Description of the Prior Art
In seatbelt systems, consideration has been given that webbings for restraining an occupant are fastened to the occupant, ends of said webbings are engaged with the vehicle, whereby the occupant is restrained in an emergency of the vehicle, so that the occupant can be protected from colliding with dangerous articles. Furthermore, to avoid obstructing the freedom for the occupant during normal running of the vehicle, ends of the webbings are secured to the vehicle through a retractor for winding up the webbings by a biasing force, and said retractor incorporates therein an inertia lock mechanism for preventing the wind-off of the webbings only in an emergency of the vehicle. Said inertia lock mechanism is constructed such that a ratchet wheel is solidly secured to a wind-up shaft for winding up the ends of the webbings, and a pawl actuated by an acceleration sensor is engaged with the ratchet wheel in an emergency of the vehicle, whereby the wind-up shaft is stopped in rotation, thus preventing the webbings from being wound off.
However, with the retractor of the type described, despite of the fact that the wind-off rotation of the wind-up shaft is stopped in an emergency of the vehicle, the webbings wound up to the wind-up shaft in layers are not stopped in wind-off until the webbings come in close contact with each other, i.e. the condition of loosely wound-up webbings takes place to unsatisfactorily restrain the occupant, so that safety of the occupant cannot be always secured.
The values of the webbings being tightened in the condition of loosely wound-up webbings tend to be increased in proportion as the values of the webbings being wound up are increased. In the passive seatbelt system in which the webbings are automatically fastened to the occupant after the occupant gets on the vehicle, the webbings are moved to a considerable extent during operation of automatical fastening of the webbings to the occupant, whereby the values of the webbings being wound up by the retractor are increased, thus the values of the webbings being tightened in the condition of loosely wound-up webbings being increased significantly.